1) Indicate whether each of the

Name:_________________________ Date:_________________ Per:_____ 1) Indicate whether each of the following processes is endothermic or exothermic, and whether q is + or - . Endo- or exothermic Sign of q (+ or -) melting of ice evaporation of ethanol condensation of steam sublimation of iodine C6H6(l) → C6H6(s)

THERMOCHEMISTRY – REVIEW

2) Complete this phase change diagram. Write in the names of the phases (SOLID , LIQUID, GAS) on the dotted lines and the phase change processes on the arrows. The little dots represent atoms or molecules of the substance.

3) Define: a) Specific heat capacity b) Molar heat capacity c) Heat of fusion

d) Heat of vaporization e) Melting f) Deposition

4) Balance the following reaction a) ____HCl + ____Ca(OH)2 Æ ____H2O + ____CaCl2 + 112 KJ b) Is this reaction exothermic or endothermic? _________________ c) How do you know?_______________________________________________________________

5) Explain the difference between heat and temperature. 6) What always happens when two objects of different temperatures come in contact? 7) Which of the following would heat up faster - 100 g water or 100 g copper (assume temp. change to be the same, specific heat of Copper is 0.35 J/g°C) _______________ Why?________________________________________________________________________________ 8) Nutritional label on a bag of roasted peanuts say that there are 854 Calories in 146 g. Find: a) Energy in Cal/g b) Energy in Joules. c) Would our bodies produce the same amount of energy from the consumption and burning of peanuts as would by burning them in a calorimetric experiment in the lab? Yes/No 1

Specific Heats: (J/g°C) ice = 2.03

water = 4.184

steam = 2.01

q = mc∆T

q = n∆H

1 cal = 4.18 J

Formulas:

iron = 0.444

aluminum = 0.897

heat gained = heat lost (calorimetry)

Problems: 1) How much heat is required to raise the temp of 205 g of water from 15.2°C to 16.2°C?

2) When 300 J of energy is lost from a 125g object, the temperature decreases from 45°C to 40°C. What is the specific heat of this object?

3) What mass of 67.5°C iron must be added to 235 g of 5.00°C water to make the final temp of both come out to be 15.0°C? (Hint: Calorimetry)

4) How much energy is absorbed by 15 g of ice being melted? H2O (s) Æ H2O (l)

{∆Hf = 6.01 kJ / 1 mol}

5) How much heat is necessary to change 5.0g of water at 100oC to steam at 100oC? {∆Hv water = 2260 J/g}

6) The specific heat of lead is 0.129 J/g-°C. Find the amount of heat released when 2.4g of lead are cooled from 37.2°C to 22.5°C.

7) How many kJ of energy are needed to raise the temperature of 165g of water from 10.5°C to 47.32°C? (Hint: convert J to KJ in the final step)

8) When nitrogen gas and hydrogen gas are heated in a bomb calorimeter to form ammonia gas, the temperature of the bomb calorimeter and the water it contains incereases. Calorimetric calculations show that 46.1kJ of heat is released for each mole of ammonia that forms during the reaction. Write a thermochemical equation for the reaction. 2

9) Refer to the graph and answer the following questions: a) What is the freezing point of this substance?_______ b) At what temperature would this sample finish boiling? _________

10) Refer to the graph and answer the questions that follow: b) What is happening to the kinetic energy of the molecules in the sample during section 1-2? Increases/Decreases c) As a substance goes through section (1-2), what happens to the distance between the particles? Increases/Decreases d) What would be the name of the process happening during section (3-5) if time were going the other way?

a) What is occurring between each of the following: a) 1 – 3 b) 3 – 7 c) 12 – 15 d) 15 – 16 e) 7 – 12

e) When this substance is melting, the temperature of the solid-liquid mixture remains constant because: a. Heat is not being absorbed b. The ice is colder that the water c. Heat energy is being converted to potential energy d. Heat energy is being converted to kinetic energy

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